Bundled flexible flat circuit cable

ABSTRACT

A bundled flexible flat circuit cable includes a flexible substrate that forms at least one cluster section having an end forming at least one first connection section and an opposite end forming at least one second connection section. Both the first and second connection sections or one of the first and second connection sections form a stack structure. The flexible substrate can be of a structure of single-sided or double-sided substrate and may additionally include an electromagnetic shielding layer. A bundling structure is provided to bundle the cluster section at a predetermined location to form a bundled structure. The bundling structure can be made of a shielding material, an insulation material, or a combination of shielding material and insulation material.

RELATED APPLICATIONS

This application is a Divisional patent application of co-pendingapplication Ser. No. 12/729,677, filed on 23 Mar. 2010, now pending. Theentire disclosure of the prior application, Ser. No. 12/729,677, fromwhich an oath or declaration is supplied, is considered a part of thedisclosure of the accompanying Divisional application and is herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a single transmission flat cable, andin particular to a bundled flexible flat circuit cable with a stackstructure.

BACKGROUND OF THE INVENTION

A conventional flat cable comprises a plurality of conductors coveredwith insulation arranged to joint each other in a side-by-side fashionto form a cable having a flat structure. The flat cable is commonly usedfor transmission of signal in a variety of electrical appliances,electronic facility, computer facility, and communication facility.

Recently, flexible circuit board technology has also been applied toconstruct flat cables. The flexible circuit-board flat cables that arecommonly used currently are constructed in different configurations thatare either a single-sided board, a double-sided board, or amultiple-layered board, in order to meet the needs of applications thatrequire different numbers of conductors for signal transmission.

Adopting a flat cable that has a flat structure to serve as a signaltransmission line constitutes no severe problem in practicalapplications where the flat cable needs to extend through an elongatespace. However, lots of existing electronic or communication devices usea hinge structure that has a bore. For example, in the structure designsof various consumer electronic devices, such as notebook computers,liquid crystal displays, digital cameras, mobile phones, touch panels,or other electronic devices, a cover or a screen is coupled to a body ofthe electronic device with a hinge structure. To allow a signal to betransmitted from the body of the electronic device to the cover or thescreen, the state-of-the-art techniques use a miniaturized flat cable orbundled extra thin leads to serve as a signal transmission line. In theapplications mentioned previously, adopting the conventional flat cableconstitutes problems, for example, rotation of the hinge beingnegatively affected by the existence of the conventional flat cable,insufficient flexibility of the conductors or leads, poor durabilityagainst flexing of the conductors or leads. Due to these problems, thepresent inventor provided various flexible flat circuit cables that havea bundled structure and a cluster section. The cluster section iscomposed of a plurality of cluster strips formed by slitting a flexiblesubstrate in an extension direction.

SUMMARY OF THE INVENTION

Using a flexible flat circuit cable having a bundled structure and acluster section meets most of the needs discussed above. However,certain problems exist. For example, in an attempt to set a flexibleflat circuit cable in a hinge of an electronic device, extending aconnection socket or a terminal plug provided at an end of the flatcable through the small diameter of the bore of the hinge becomes aproblem that is hard to handle. Further, even though the connectionsocket or the terminal plug can readily extend through the smalldiameter of the hinge bore, the cluster of strips is susceptible toarbitrary distortion and external electromagnetic interference.

In view of the drawbacks of the known techniques, an objective of thepresent invention is to provide a bundled flexible flat circuit cablehaving a stack structure, whereby the stack structure allows the flatcable to reduce a width dimension of an end of the flat cable so thatthe end of the flexible flat circuit cable can easily extend through abore defined in a hinge.

Another objective of the present invention is to provide a bundledflexible flat circuit cable that exhibits excellent electromagneticshielding characteristics, which when combined with the features ofstacking and bundling of the flat cable of the present invention, allowsfor the formation of an electromagnetic shielding layer on a flexiblesubstrate of the flat cable and may also allow for forming a bundledstructure with electromagnetic shielding material.

The solution adopted in the present invention to overcome the problemsof the conventional techniques comprises a flexible substrate that formsat least one cluster section. The cluster section is composed of pluralcluster strips that are formed by slitting the flexible substrate alongan extension direction of the flexible substrate. The cluster sectionhas an end forming at least one first connection section and an oppositeend forming at least one second connection section. Both the first andsecond connection sections or one of the first and second connectionsections comprises a stack structure, which is formed by folding twoopposite side stacking zones or one of the two opposite side stackingzones of the connection section along a respective fold line to have theside stacking zone stacked on at least a portion of a central zone ofthe connection section that is located between the two opposite sidestacking zones.

In an embodiment of the present invention, the flexible substrate can beof a single-sided or double-sided structure and may additionallycomprise an electromagnetic shielding layer. A bundling structure isprovided to bundle the cluster section at a predetermined location toform a bundled structure. The bundling structure can be made of ashielding material, an insulation material, or a combination ofshielding material and insulation material.

According to the present invention, a stacked arrangement is selectivelyformed so that the configuration of a signal transmission flat cable canbe made to reduce the width dimension of an end of the flexible flatcircuit cable. Thus, the sized reduced end of the flexible flat circuitcable can be easily extended through a small diameter of a bore definedin a hinge when the flexible flat circuit cable is being mounted to thehinge structure. The bundling structure that bundles the cluster sectionof the flexible flat circuit cable together provides a function torestrict flexing of each cluster strip of the cluster section of theflexible substrate and also offers electromagnetic shielding to thecluster section.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be apparent to those skilled in the art byreading the following description of preferred embodiments of thepresent invention, with reference to the attached drawings, in which:

FIG. 1 is a perspective view of a bundled flexible flat circuit cable inaccordance with the present invention in an expanded form;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view showing a flexible substrate arrangedas a double-sided circuit substrate in accordance with the presentinvention;

FIG. 4 is a perspective view showing the bundled flexible flat circuitcable of the present invention with terminal connection sections thereofin a stacked condition;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4;

FIG. 6 is a perspective view showing an embodiment of the bundledflexible flat circuit cable of the present invention where both a firstconnection section and a second connection section are each providedwith a connection socket;

FIG. 7 is a perspective view showing an embodiment of the presentinvention where a connection section is connected respectively throughcluster strips of two separate cluster sections to two oppositeconnection sections;

FIG. 8 is a cross-sectional view showing a bundling structure wrappingaround cluster strips of a cluster section of a flexible substrate inaccordance with the present invention;

FIG. 9 is a perspective view showing an application of the presentinvention in a mobile phone that has a hinge structure;

FIG. 10 is a cross-sectional view showing an outer insulation layerwrapping around an outer surface of an electromagnetic shielding layerof the bundling structure shown in FIG. 8; and

FIG. 11 is a cross-sectional view showing a cluster section of aflexible substrate of the present invention first wrapped by an innerinsulation layer, an electromagnetic shielding layer wrapping around anouter surface of the inner insulation layer, and an outer insulationlayer further wrapping around an outer surface of the electromagneticshielding layer; and

FIG. 12 is a perspective view showing a bundled flexible flat circuitcable in accordance with the present invention where a helical bundlingstructure wraps around a predetermine location of a cluster section ofthe bundled flexible flat circuit cable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings and in particular to FIG. 1, which showsa perspective view of a bundled flexible flat circuit cable inaccordance with the present invention in an expanded form, and FIG. 2,which shows a cross-sectional view taken along line 2-2 of FIG. 1, thebundled flexible flat circuit cable constructed in accordance with thepresent invention, generally designated at 100, comprises a flexiblesubstrate 11, which extends a predetermined length in an extensiondirection I. The flexible substrate 11 has a first surface 11 a and anopposite second surface 11 b. A first conductive layer 12 and a firstinsulation layer 13 are sequentially formed on the first surface 11 a ofthe flexible substrate 11. In a preferred embodiment of the presentinvention, an electromagnetic shielding layer 14 is further formed onthe first insulation layer 13. The electromagnetic shielding layer 14may selectively and locally covers a predetermined area of an externalsurface of the first insulation layer 13 to provide electromagneticshielding for protecting electrical signals.

The flexible circuit substrate shown in FIG. 2 has a structure ofsingle-sided circuit substrate. However, the present invention isequally applicable to a double-sided circuit substrate. In a structureof double-sided circuit substrate (see FIG. 3), a second conductivelayer 15 and a second insulation layer 16 are sequentially formed on thesecond surface 11 b of the flexible substrate 11. Further, in thestructure of double-sided circuit substrate, a signal jumper structuremay be additionally provided. For example, a through hole 17 is definedthrough both the first surface 11 a and the second surface 11 b of theflexible substrate 11 at a predetermined location and a conductivesubstance 18 is formed on an inside surface of the through hole 17 toallow for selective signal communication between the first conductivelayer 12 and the second conductive layer 15 of the first surface 11 aand the second surface 11 b of the flexible substrate 11. The structureof double-sided circuit substrate can be alternatively realized bybonding two single-sided circuit substrates in a back-to-back manner.

The flexible substrate 11 is divided in the extension direction I into afirst connection section 2, a second connection section 3, and a clustersection 4 between the first and second connection sections 2, 3. Inother words, the first connection section 2 is located at an end of thecluster section 4, while the second connection section 3 is located atan opposite end of the flexible substrate 11 that is opposite to thefirst connection section 2.

The cluster section 4 comprises a plurality of cluster strips 41 that isformed by slitting the flexible substrate 11 in the extension directionI. All or some of the cluster strips 41 is provided with a signal lineto serve as an electrical signal transmission path between the firstconnection section 2 and the second connection section 3. The clustersection 4 may selectively form a plurality of tear stop holes 214 atsuitable locations of terminals of all or some cluster strips 41 (forexample, in the first connection section 2 and the second connectionsection 3) in order to protect the cluster strips 41 from damage causedby undesired tearing along the slitting during the assembling or use ofthe flexible substrate 11.

The first connection section 2 comprises a stack structure 20. With alsoreference to FIGS. 4 and 5, the stack structure 20 divides the firstconnection section 2 into a central zone 21 and side stacking zones 22,23 located on opposite sides of the central zone 21. The side stackingzones 22, 23 of the two sides or one of the side stacking zones 22, 23of one side of the central zone 21 is allowed to fold along a physicalor imagination fold line 212, 213 to fold in a direction toward thecentral zone 21 so as to have the side stacking zones 22, 23 stackedunder the central zone 21 or on a portion of the central zone 21. Inthis way, the width of the first connection section 2 that is adimension measured in a direction perpendicular to the extensiondirection I of the flexible substrate 11 is reduced. The secondconnection section 3 may also be provided with a similar stack structureto allow two side stacking zones 32, 33 that are located on oppositesides of a central zone 31 of the second connection section 3 to bestacked under the central zone 31 or on a portion of the central zone31. After the stacking operation, a structure shown in FIG. 4 is formed.

In a practical application, the first connection section 2 and thesecond connection section 3 may be provided with different types ofconnection socket or terminal plug at predetermined locations thereof.For example, as shown in the embodiment of FIG. 1, a connection socket211 is set on the central zone 21 of the first connection section 2,while the side stacking zone 32 of the second connection section 3 formsa terminal plug 321 at a side edge thereof. It is certainly andalternatively feasible to provide same type of connection socket orterminal plug at both the first connection section 2 and the secondconnection section 3. For example, as shown in the embodiment of FIG. 6,the central zone 21 of the first connection section 2 is mounted with aconnection socket 211 and the side stacking zone 31 of the secondconnection section 3 is also provided with a connection socket 311.

Further, the connection sections and the cluster section of the flexiblesubstrate can be arranged in a one-to-one fashion, or alternatively aone-to-plurality fashion can be adopted. For example, in the embodimentof FIG. 1, an arrangement that a connection section is connected by asingle cluster section to an opposite connection section is provided.However, in the embodiment of FIG. 7, a different arrangement that asecond connection section 3 is connected by cluster strips 41 of acluster section 4 to a first connection section 2 and is also connectedby cluster strips 41 a of an additional cluster section 4 a to anadditional first connection section 2 a is provided. Practicalapplication may need different variations to meet differentrequirements.

In an embodiment of the present invention, at least one bundlingstructure 5 is provided to loop around or bundle the cluster section 4of the flexible substrate 11 at a predetermined location (see FIG. 4) soas to bundle the cluster strips 41 of the cluster section 4 together toform a bundled structure. FIG. 8 shows a cross-sectional view takenalong line 8-8 of FIG. 4. In a preferred embodiment of the presentinvention, the bundling structure 5 comprises an electromagneticshielding layer 51. In other words, the bundling structure 5 comprises astructure that is made of an electromagnetic shielding substance loopingaround the predetermined location of the cluster section 4, so as toloop or bundle the cluster strips 41 of the cluster section 4 togetherto form a bundled structure and also to provide electromagneticshielding to the cluster section 4. The bundling structure 5 can bealternatively made of an insulation material (such as a water-proofplastic band) or a composite combination of electromagnetic shieldingsubstance and insulation material can be used to form the bundlingstructure.

FIG. 9 illustrates an example application of the present invention in amobile phone that has a hinge structure. As shown, the bundled flexibleflat circuit cable 100 is set through a hinge structure 6 with thecluster strips 41 of the cluster section 4 of the flexible substrate 11and the first connection section 2 and the second connection section 3are respectively set on opposite sides of the hinge structure 6. Withthe electromagnetic shielding effect provided by the electromagneticshielding layer 51 of the bundling structure 5, electromagneticinterference occurring in the electrical signals transmitted through atransmission path defined by the cluster strips 41 of the clustersection 4 can be effectively eliminated.

In an alternative application, an outer surface of the electromagneticshielding layer 51 may be further surrounded by an outer insulationlayer 52 (see FIG. 10), or alternatively, the cluster section 4 of theflexible substrate 11 is wrapped around by an inner insulation layer 53,an electromagnetic shielding layer 51 is then wrapped around an outersurface of the inner insulation layer 53, and finally an outerinsulation layer 54 is further wrapped around an outer surface of theelectromagnetic shielding layer 51 (see FIG. 11).

The bundling structure 5 used in the previous embodiments is made in theform of a thin sheet, which is wrapped in a wrapping direction II aroundthe predetermined location of the cluster section. Alternatively, ahelical wrapping structure may be employed to form the bundlingstructure. As shown in FIG. 12, a slender elongate band made of anelectromagnetic shielding material is helically wrapped in aninclination direction III around the cluster strips 41 of the clustersection 4 to form a helical bundling structure 5 a. The elongate bandcan be made of an electromagnetic shielding material including a pieceof electrically conductive cloth, silver foil, aluminum foil, copperfoil, and other metal foils that exhibit electromagnetic shieldingcharacteristics.

Although the present invention has been described with reference to thepreferred embodiments thereof, it is apparent to those skilled in theart that a variety of modifications and changes may be made withoutdeparting from the scope of the present invention which is intended tobe defined by the appended claims.

1. A bundled flexible flat circuit cable, comprising: a flexiblesubstrate, which extends in an extension direction and has a firstsurface and a second surface; a first conductive layer, which is formedon the first surface of the flexible substrate; at least a firstconnection section, which is formed on an end of the flexible substrate;at least a second connection section, which is formed on an opposite endof the flexible substrate that is opposite to the first connectionsection; at least a cluster section, which connects between the firstconnection section and the second connection section and comprises aplurality of cluster strips that are formed by slitting the flexiblesubstrate in the extension direction; a first insulation layer, which isformed on the first conductive layer; and at least a bundling structure,which bundles the cluster section at a predetermined location to wrapthe cluster strips of the cluster section together to form a bundledstructure, the bundling structure comprising an elongate strap helicallywrapped in an inclination direction around the predetermined location ofthe cluster section.
 2. The bundled flexible flat circuit cable asclaimed in claim 1, wherein the first connection section comprises oneof a terminal plug and a connection socket formed thereon.
 3. Thebundled flexible flat circuit cable as claimed in claim 1, wherein thesecond connection section comprises one of a terminal plug and aconnection socket formed thereon.
 4. The bundled flexible flat circuitcable as claimed in claim 1, further comprising an electromagneticshielding layer on at least one of the first insulation layer and thesecond surface of the flexible substrate.
 5. The bundled flexible flatcircuit cable as claimed in claim 1, further comprising: a secondconductive layer, which is formed on the second surface of the flexiblesubstrate; and a second insulation layer, which is foamed on the secondconductive layer.
 6. The bundled flexible flat circuit cable as claimedin claim 5, further comprising an electromagnetic shielding layer on atleast one of the first insulation layer and the second insulation layer.7. The bundled flexible flat circuit cable as claimed in claim 1,wherein the bundling structure is made of an electromagnetic shieldingmaterial.
 8. The bundled flexible flat circuit cable as claimed in claim1, wherein the bundling structure is made of an insulation material. 9.The bundled flexible flat circuit cable as claimed in claim 1, whereinthe bundling structure comprises: an inner insulation layer, which wrapsaround the cluster section; and an electromagnetic shielding layer,which wraps around an outer surface of the inner insulation layer. 10.The bundled flexible flat circuit cable as claimed in claim 9, whereinthe electromagnetic shielding layer is further wrapped by an outerinsulation layer.
 11. The bundled flexible flat circuit cable as claimedin claim 1, wherein the bundling structure comprises: an electromagneticshielding layer, which wraps around the cluster section; and an outerinsulation layer, which wraps around an outer surface of theelectromagnetic shielding layer.